The present invention relates to methods and systems for providing number portability in a communications network. More particularly, the present invention relates to a universal number portability routing node for providing number portability in a communications network.
Number portability (NP) gives telephone service subscribers the ability to change service providers without changing their directory numbers. More specifically, the generic term NP is actually representative of three basic number porting scenarios: service provider portability, which allows subscribers to change service providers without changing their phone numbers; service portability, which allows subscribers to change from one type of service to another (e.g., analog to integrated services digital network (ISDN) without changing their phone numbers; and geographic portability, which allows subscribers to move from one physical location to another without changing their phone numbers.
In the current, non-NP environment, a telephone number performs two basic functions: it identifies the customer, and it provides the network with information necessary to route a call to that customer. Number portability solutions separate these two functions, thereby providing the means for customers to keep the same directory number when changing service providers.
By separating customer identification from call routing, NP gives customers the flexibility to respond to pricing and service changes offered by rival carriers. Accordingly, it is anticipated that NP will promote local-exchange competition, which in turn will benefit all customers, as has already been the case with the long-distance market. As NP solutions are implemented, competition in the local-exchange market is expected to drive down the cost of service, encourage technological innovation, stimulate demand for telecommunications services, and boost economic growth.
A number of interim number-portability methods, such as remote call forwarding and direct inward dialing exist today. However, these methods have several disadvantages: longer call set-up times, increased potential for call blocking, continued reliance on the incumbent local exchange carrier""s (LEC""s) network, loss of feature functionality, as well as substantial on-going costs to the new local service provider. Among the more long-term NP solution approaches currently being offered, triggered NP technology is the most relevant to a discussion of the present invention.
Triggered NP solutions, as indicated by the name, require that both the xe2x80x9cnewxe2x80x9d and xe2x80x9coldxe2x80x9d service providers implement a trigger function in their respective end offices. The xe2x80x9coldxe2x80x9d service provider switch (often referred to as the donor switch) administers an NP trigger on the ported subscriber""s directory number. When activated, this trigger causes the end office switch to formulate an NP query that is subsequently launched into the SS7 network. This NP query is ultimately delivered to an NP database that contains information related to service provider associated with the dialed number. More particularly, the NP database performs a lookup based on a portion of the called party dialed digits. A location routing number or routing number (RN) is returned by the NP database. The routing number identifies the end office of the service provider currently serving the called party. The RN value is then sent back to the end office that originated the NP query. Upon receipt of the RN containing message, the originating end office proceeds with call setup operations using the RN as a destination address for all subsequent messages associated with the call.
Shown in FIG. 1 is an example of a telecommunications network generally indicated by reference numeral 100 that employs a triggered NP solution similar to that described above. Telecommunications network 100 includes an originating end office (EO) 110, a recipient terminating EO 112, a donor terminating EO 113, a tandem switching office 114, a signal transfer point (STP) 116, a service control point (SCP) based NP database 118, a calling party 120, and a called party 122. In this example, it is assumed that called party 122 has had local phone service ported from a service provider that owns EO 113 to a service provider that owns EO 112. Consequently, it is implied that the service responsibility for called party 122 was transferred from the donor EO 113 to the recipient EO 112 at some point in the past. As such, EO 112 is now assumed to service called party 122.
As such, FIG. 1 illustrates a simplified signaling message flow sequence associated with the setup of a call from calling party 120 to called party 122. When calling party 120 goes off-hook and dials the telephone number associated with called party 122, originating EO 110 analyzes the dialed digits and recognizes that the dialed number falls within an exchange that contains ported subscribers. Consequently, the originating EO 110 formulates an NP query message M1 and sends this query message to the STP 116. Those skilled in the art of SS7 telecommunication networks will appreciate that such NP queries and responses are typically in the form of transaction capabilities application part (TCAP) protocol signaling messages. As the TCAP protocol is well known and widely employed in the communication networks presently contemplated, a detailed discussion of the TCAP signaling protocol is not included herein. A detailed discussion of SS7 TCAP signaling message structures and their associated function can be found in Signaling System #7 by Travis Russell, McGraw-Hill Publishing 1998.
Returning now to the message flow shown in FIG. 1, NP query message M1 is received by STP 116 and subsequently routed to SCP-NP database node 118 as NP query message M2. The NP query message M2 is processed by SCP-NP database node 118, and an NP response message M3 is formulated and sent back to STP 116. It should be appreciated that NP response message M3 contains an RN associated with recipient EO 112, which is the EO currently servicing Called Party 122. Tandem office 114 is particularly significant from a call setup standpoint, in that a voice trunk connection through tandem 114 will ultimately be required in order to establish a voice circuit with terminating EO 112 that is currently serving the called party 122. NP response message M3 is received by the STP 116 and subsequently routed to the originating EO 110, as NP response message M4. The originating EO 110 processes NP response message M4, and uses the RN information contained therein to formulate and send a call setup message M5. Once again, those skilled in the art of SS7 telecommunication networks will appreciate that such call setup messages are typically of ISDN user part (ISUP) format, and as the ISUP signaling protocol is well known and widely employed in the telecommunications industry, a detailed explanation of this protocol is not provided herein. Once again, the above-mentioned text, Signaling System #7, by Travis Russell, provides a detailed explanation of the ISUP signaling protocol.
Returning to FIG. 1, STP 116 receives message M5 and subsequently message transfer part (MTP) routes the message to tandem office 114 as message M6. Tandem office 114 examines and processes the message and formulates a message M7. Message M7 is sent to STP 116, which in turn MTP routes the message to terminating EO 112 as message M8. Those skilled in the art of telecommunications network operations will appreciate that additional call setup messages, not shown in FIG. 1, may be necessary to administer a complete a telephone call between the calling party 120 and the called party 122. The signaling message flow shown in FIG. 1 is intended only to generally illustrate a conventional NP translation process. As these additional signaling messages are not particularly relevant to the design and operation of the present invention, a detailed discussion of call setup and teardown procedures in an SS7 telecommunications network is not provided herein.
While the approach described above is functionally capable of providing network operators with number portability translation service, this approach necessarily requires that an originating end office switch have the ability to trigger an NP query and to interpret the subsequent NP response. In practice, this means that an originating end office switch must be capable of generating and launching an NP query message into the signaling network. As such, this also implies that an originating end office switch has the ability to receive and process NP response messages that are generated by service nodes within the signaling network.
In addition to the problems associated with trigger-based number portability solutions, another problem associated with providing number portability service is that different countries and telecommunications standards organizations specify different parameters for storing number portability status information. For example, International Telecommunications Union (ITU) Recommendation Q.769.1, ISDN User Part Enhancements for the Support of Number Portability, December 1999, specifies a number portability forward information (NPFI) parameter for storing number portability status information. However, since this parameter is optional, some countries do not use this parameter to store number portability status information. In such countries, number portability status information may be stored in other fields of a call signaling message. For example, in Spain, the nature of address (NOA) parameter is used to store number portability status information. In light of these and other parameters for storing number portability status information, there is no universal method for determining whether number portability processing is required.
In light of these and other difficulties with conventional number portability solutions, there exists a need for scalable methods and systems for providing universal number portability. Such methods and systems preferably combine the aspects of not requiring an end office trigger with the ability to process non-standard number portability specifiers.
A triggerless number portability (TNP) routing node includes a communication module for receiving a message from an end office over a communications network. A gateway screening (GWS) process determines that the message is a call setup message, and in response to determining that the message is a call setup message, forwards the call setup message over a communications bus for further processing. A number portability (NP) database contains routing numbers (RNs) for SS7 signaling points associated with ported subscribers. A universal portability module (UPM) receives the message from the communications bus, extracts the called party address from the message, examines a number of parameters contained within the message, and, based on one or more of these message parameter values, may perform a lookup in the NP database using the called party address to obtain an RN. In the event that an RN is returned from the NP database, the message is modified to include the RN and subsequently routed. If a call setup message is received which has already obtained an NP translation, a TNP routing node of the present invention is adapted to perform an additional number portability translation in the event that the RN contained within the message is associated with a gateway signaling point (i.e. tandem switch) that is in the home network of the TNP routing node, as opposed to a signaling end point (i.e., an end office or mobile switching center).
Accordingly, it is an object of the present invention to provide a triggerless number portability (TNP) routing node capable of analyzing a variety of fields in a call setup message in order to determine the need for a number portability (NP) translation.
It is another object of the invention to provide a number portability processing method wherein an NP database lookup returns a routing number (RN) for a tandem gateway or to a signaling end point.
It is yet another object of the invention to provide an NP processing method wherein an RN database lookup is performed prior to performing an NP database lookup to determine whether an RN in a received call setup message corresponds to the home network of the node performing the lookup or belongs to another network.
Some of the objects of the invention having been stated hereinabove, other objects will become evident as the description proceeds, when taken in connection with the accompanying drawings as best described hereinbelow.